Add the dualpath-as-single-machine site toggle

Most facilities consider a Dualpath pair one physical dual-bay machine.
New site setting dualpath_single_machine (default on): the machines
list, dashboard counts, machines-by-type report, and floor map collapse
each pair to its primary bay (lower assetnumber), with combined
2007 / 2008 labels; pagination totals stay honest. Detail pages remain
per-bay and always show a dual-bay sibling banner linking the partner.
Pair resolution lives in core services and joins the plugin contract
surface (0.8.0 -> 0.9.0).

On the WJ dataset: 31 pairs collapse, machine counts 262 -> 231, map
470 assets. Toggle verified live in both states, left on.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/views/settings/SiteSettings.vue

@@ -44,7 +44,8 @@ const LABELS = {
   facility_name: 'Facility Name',
   pc_access_domain: 'PC Access Domain',
   employeeid_pattern: 'Employee ID Pattern',
-  printer_hostname_template: 'Printer Hostname Template'
+  printer_hostname_template: 'Printer Hostname Template',
+  dualpath_single_machine: 'Dualpath as Single Machine'
 }
 function prettyLabel(key) {
   return LABELS[key] || key
@@ -53,7 +54,8 @@ function prettyLabel(key) {
 // Inline help for site fields that need more than the stored description.
 const HELP = {
   employeeid_pattern: 'Regular expression that a scanned/typed employee ID must match to be recognized. Default: ^\\d{9}$ (9 digits). An invalid regex is ignored and the default is used.',
-  printer_hostname_template: 'Template for generating printer hostnames from an IP. Use {ip} where the dash-separated IP goes. Example: Printer-{ip}.printer.geaerospace.net'
+  printer_hostname_template: 'Template for generating printer hostnames from an IP. Use {ip} where the dash-separated IP goes. Example: Printer-{ip}.printer.geaerospace.net',
+  dualpath_single_machine: 'Treat a Dualpath pair (a dual-bay machine with one controller) as a single machine in lists, counts, and the floor map. Both bay records are always kept; detail pages stay per-bay with a sibling banner. Enter true or false. Default: true.'
 }
 function fieldHelp(key) {
   return HELP[key] || ''